This study introduces the evaluation of root system size (RSS) for the breeding of barley, in particular for drought tolerance. In 2005-2008, 10-22 varieties of spring barley (Hordeum vulgare L.) were evaluated at two locations (only one in 2007) for RSS by its electric capacity. The RSS was compared with the yield and the quality of the varieties in state registration trials at 7-19 stations each year. Varieties with a greater RSS than the others varieties had a significantly higher yield in the dry year of 2007. Similar relationships between RSS and yield in the other years were found in only some of the environments. Malting varieties with a greater RSS had significantly higher contents of starch, saccharide extracts and malt extracts, as well as higher yields of protein and starch in 2007. It can be concluded that a small RSS is related to a low grain yield and malt quality in dry environments, even in genetically diverse varieties.

No abstract

In a three‐year period, protein content, polysaccharides and values of the selected malting parameters were determined in 12 varieties of barley. Hardness was assessed using the particle size index (PSI) and a Do‐Corder apparatus (BRA). Significant differences in the levels of hardness between the varieties were detected. Hardness was affected by variety from 37% (PSI) and 71% (BRA). Significant correlations were determined between the PSI and extract content (0.64***), Kolbach index (0.66***), friability (0.57***), β‐glucans in wort (−0.51***) and colour of malt (0.57***). Significant correlations were found between BRA and content of non‐starch polysaccharides in caryopses (0.64***), extract (−0.62***), Kolbach index (−0.70***), friability (−0.70***), β‐glucans in wort (0.79***) and wort colour (−0.56***). Correlation was determined between hardness and malting quality index (PSI 0.51***, BRA −0.71***).

Several methods were used for the characterization of starch granules isolated from barley kernels. A procedure based on a combination of alkaline digestion, toluene treatment and filtration over sieves with pore diameters of 70 and 40 μm was used for isolation and purification of starch granules from kernels. The released starch granules were characterized by various methods: scanning electron microscopy (SEM), image analysis of optical microscopy data (IAOM), low angle laser light scattering (LALLS), and gravitational field‐flow fractionation (GFFF). All methods showed the bimodal size distribution of the isolated starch granules, however, they differed in the ratio of large and small starch granules. LALLS and GFFF were also used for determination of the ratio of large and small starch granules (ratio A/B) isolated from two malting barley cultivars Kompakt and Akcent. Both techniques determined the higher ratio A/B for the cultivar Akcent. SEM was also used to examine the extent of digestion. The micrographs indicate that a significant proportion mainly of small granules are still embedded into residues of endosperm and a more extensive digestion must be performed to release all starch granules from barley kernels.

Over the 5-year period (2000-2004), a significantly higher beta-glucan content was detected in the waxy varieties Washonubet, Wabet, and Wanubet (6.8-7.6%) and lines formed by crossing these varieties with malting varieties (5.8-7.1%). Conversely, the non-waxy hulled malting-type varieties Kompakt (4.0%) and Krona (4.3%) had significantly lower contents of beta-glucan. The observations also showed that concentrations of beta-glucans in 2000-2004 were significantly affected not only by varieties, but also environmental conditions in the growing periods and interactions of these two factors. Higher precipitation during the flowering time and grain filling period and lower temperatures during the flowering time in 2002 had negative effects on concentration of beta-glucans. Conversely, drier and warmer weather in 2003 enhanced the content of beta-glucans. The results show that it is possible to increase the content of beta-glucan in spring barley grain by implementing selective breeding practices. Compared to the parental malting varieties, the mean content of beta-glucans in F(4)-F(8) generations was increased by 1.8 and 2.0% by recombination in lines Kompakt x Wabet and Wanubet x Krona, respectively. Significant effect of environmental conditions and their interactions with varieties indicated the necessity to assess standard qualities of barley as a food material.